1. Field of the Invention
The present invention relates to a hard disk drive (HDD) for magnetically reading/writing digital data, and more particularly to an intelligent HDD with a track pitch adjustment to cope with operational errors.
2. Description of the Related Art
HDDs are widely used as auxiliary memory devices of computer systems because of providing means for accessing a large amount of data at a high speed. The HDD has a plurality of magnetic disks, each of which in turn has a plurality of tracks concentrically arranged to store the data. These tracks are accessed by the heads(or data transducers) to read, write or erase the data on the disks. The signals picked up by the heads are usually distorted by various factors such as the kinds and recording density of the magnetic disks, the positions and types of the heads, the ratio of signal to noise (S/N ratio), signal bands, interferences, vibrations, etc. Particularly, such distortions become more serious as the storage capacity of the disk is enhanced so as to increase the number of the tracks, inducing high data recording density to cause interferences between data bits resulting in reduction of the signal amplitude. Furthermore, the data recording densities of the tracks become increased toward the center of the tracks so as to reduce and distort the signal amplitude due to the signal interferences and overlaps.
One of the methods to increase the data recording densities of the disks in order to obtain an HDD with a high data access speed and high storage capacity is to increase the number of tracks per inch (TPI) and bits per inch (BPI), which involves taking the flying height of the heads into account. A typical HDD requires the flying height of the heads to be about 2 micro-inches. However, this may be affected by various factors such as the head gimbal assembly (HGA), variation after stacking, etc. Thus, if the flying height of the head becomes higher than the normal operation range, the dynamic characteristics relating to the read/write operation such as track average amplitude (TAA), bit shift, etc., are changed so that the data transferred from the host may be erroneously written on the disk or so as to cause data reading errors.